-
University of Groningen
A Demonstration Project on Driving with Reduced Visual Acuity
and a Bioptic TelescopeSystem in the NetherlandsMelis, Bart;
Kooijman, Aart; Brouwer, Wiebo; Busscher, Rens B.; Bredewoud, Ruud
A.;Derksen, Peter H.; Amersfoort, Anoeska; IJsseldijk, Martin A.M.;
Delden, Geert W. van;Grotenhuis, Thea H.P.A.Published in:Visual
Impairment Research: The official publication of the International
Society for Low-vision Research andRehabilitation ISL
DOI:10.1080/13882350802053707
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Kooijman, A. C., Brouwer, W. H., Busscher, R. B., Bredewoud, R. A.,
Derksen, P.H., ... Witvliet, M. D. (2008). A Demonstration Project
on Driving with Reduced Visual Acuity and a BiopticTelescope System
in the Netherlands. Visual Impairment Research: The official
publication of theInternational Society for Low-vision Research and
Rehabilitation ISL, 10(1), 7-22. DOI:10.1080/13882350802053707
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A Demonstration Project on Driving with Reduced VisualAcuity and
a Bioptic Telescope System in theNetherlandsBart J. M.
Melis-Dankers ab; Aart C. Kooijman ab; Wiebo H. Brouwer b; Rens
B.Busscher b; Ruud A. Bredewoud c; Peter H. Derksen a; Anoeska
Amersfoort a;Martin A. M. Ijsseldijk a; Geert W. van Delden a; Thea
H. P. A. Grotenhuis a; JaapM. D. Witvliet aa Royal Visio, National
Foundation for the Visually Impaired and Blind, Huizen, The
Netherlandsb University of Groningen, Groningen, The
Netherlandsc Netherlands Bureau of Driving Skills Certificates,
Rijswijk, The Netherlands
Online Publication Date: 01 March 2008
To cite this Article: Melis-Dankers, Bart J. M., Kooijman, Aart
C., Brouwer, Wiebo H., Busscher, Rens B.,Bredewoud, Ruud A.,
Derksen, Peter H., Amersfoort, Anoeska, Ijsseldijk, Martin A. M.,
van Delden, Geert W.,Grotenhuis, Thea H. P. A. and Witvliet, Jaap
M. D. (2008) 'A Demonstration Project on Driving with Reduced
VisualAcuity and a Bioptic Telescope System in the Netherlands',
Visual Impairment Research, 10:1, 7 — 22
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Visual Impairment Research, 10:7–22, 2008Copyright ©c Informa
Healthcare USA, Inc.ISSN: 1388-235X print / 1744-5167 onlineDOI:
10.1080/13882350802053707
A Demonstration Project on Driving withReduced Visual Acuity and
a BiopticTelescope System in the Netherlands
Bart J. M. Melis-Dankers, PhD,and Aart C. Kooijman, PhDRoyal
Visio, NationalFoundation for the VisuallyImpaired and Blind,
Huizen,The Netherlands; andUniversity of Groningen,Groningen, The
Netherlands
Wiebo H. Brouwer, PhD,and Rens B. Busscher, MScUniversity of
Groningen,Groningen, The Netherlands
Ruud A. Bredewoud, MDNetherlands Bureau of DrivingSkills
Certificates, Rijswijk,The Netherlands
Peter H. Derksen, BSc,Anoeska Amersfoort,Martin A. M.
Ijsseldijk,Geert W. van Delden, MSc,Thea H. P. A. Grotenhuis,and
Jaap M. D. WitvlietRoyal Visio, NationalFoundation for the
VisuallyImpaired and Blind, Huizen,The Netherlands
ABSTRACT Background: In Europe, driving a passenger car is
prohibited ifbinocular best corrected visual acuity (BCVA) is below
0.5 (20/40). Some USstates allow people with reduced visual acuity
to use a bioptic telescope systemwhen driving. The aim of our study
is to introduce a bioptic telescope systemfor driving in the
Netherlands and to investigate whether it enables people
withreduced visual acuity to gain sufficient practical fitness to
drive in a Europeansetting. Results: Out of 378 persons who applied
for information following mediaattention for the project, 160
candidates volunteered to participate. Based on theavailable
information, 36 subjects (binocular BCVA: 0.16–0.5
[20/125–20/40])were invited for assessment (vision, mobility,
cognitive function, and drivingskills). Of these, 16 did not meet
the inclusion criteria and 2 decided not toparticipate. The
remaining 18 subjects were trained in the use of a monocularbioptic
telescope (3× magnification). They all completed the predriving
trainingsuccessfully and received driving lessons from specialized
professional drivinginstructors. Eventually, 9 subjects passed the
official on-road test of practicalfitness to drive, 7 were excluded
after a number of driving lessons, and another2 withdrew on their
own initiative. Conclusion: This is the first study in Europeto
prepare subjects with reduced visual acuity to drive with the use
of a bioptictelescope system. About 55% of the preselected subjects
fulfilled all inclusioncriteria. Half of the subjects who entered
the bioptic training program passedthe official fitness to drive
test, demonstrating that they could drive smoothlyand safely in
Dutch traffic using a bioptic telescope system.
KEYWORDS Vision rehabilitation; fitness to drive; optics;
orientation and mobilitytraining; Europe
INTODUCTIONWithout a doubt, vision is crucial for the complex
task of driving a mo-
tor vehicle and constitutes the main input of information to the
driver. Re-duction of visual function can limit the ability to
drive a car safely and, forthis reason, official minimum
requirements regarding the visual capacity of
Accepted 4 February 2008
Address correspondence to Bart J.M.Melis-Dankers, PhD, Visio
NoordNederland, PO Box 144, NL-9750 ACHaren, the Netherlands.
E-mail:[email protected]
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drivers are set by legislative authorities. On the otherhand,
the ability to drive independently is very im-portant for social as
well as economic reasons1−4
and such a major privilege should not be deniedunjustly.
The exact limit of visual acuity for safe driving is dif-ficult
to determine. In the member countries of the Eu-ropean Union (EU),
driving a passenger car is currentlynot allowed for drivers with
binocular best correctedvisual acuity (BCVA) of worse than 0.5
(20/40).5 How-ever, this limiting value is not evidence based and
seemsrather arbitrary. Several previous studies showed onlyweak
relationships between visual acuity and practicalfitness to drive
or driving safety.6−12 In the study of Co-eckelbergh et al,13 25%
of the subjects with correctedbinocular visual acuity in the range
0.1–0.5 (20/200–20/40) passed the official on-road test of
practical fit-ness to drive, demonstrating that they could drive
safelyand smoothly in normal traffic. Visual acuity
correlatedsignificantly with the final driving test score, but
ac-counted for only 20% of the variance in the pass/failscore of
the practical fitness to drive test.7,14 Further-more, in a number
of US states,12,15,16 the thresholdacuity required for driving
without restrictions lies be-low the European standard and this
does not generallylead to more accidents.17 Although a visual
acuity be-low the limiting value of 0.5 (20/40) is a clear
indicationof impaired vision and needs closer inspection, these
re-sults cast doubt on the use of this limit as an automatic
FIGURE 1 Bioptic telescope system. (A) Bioptic position while
looking ahead through carrier lens. (B) Bioptic position while
lookingthrough telescope. (Photos by P.H. Derksen, Holsboer
Optometrie, Arnhem, The Netherlands.)
exclusion criterion for driving. Korb18 and Feinbloom19
already recognized the potential for a bioptic telescopesystem
(BTS or bioptic), which is the combination of asmall telescope
(typically 2×–4×) mounted in the up-per part of a carrier lens that
is made to the individual’srefractive prescription, to be used for
driving (see Fig-ure 1). This optical aid allows rapid fixation
changesbetween viewing through the carrier lens and throughthe
telescope by a slight nod of the head (typically ver-tically about
15–20 degrees). It enables the driver to sur-vey general traffic
through the normal spectacle carrierlens for most of the time (see
Figure 1A), and to use thetelescope briefly for spotting tasks such
as reading a traf-fic sign or looking far ahead to survey an
approachingintersection (see Figure 1B). A monocular bioptic
tele-scope allows a driver with moderate central vision im-pairment
but good peripheral vision to increase visualacuity instantly
without losing the overall view. A briefglance through the
telescope enables bioptic drivers togain detailed information from,
for instance, road signsand distant objects, which they are unable
to see in timewithout magnification. In contrast to the EU where
lowvision driving with a bioptic is not allowed, it is permit-ted
in 36 US states,15,16,20 where there are more than4000 bioptic
drivers.21 However, because of differencesin, for instance,
standards of driving, traffic density, androad design, it is not a
priori evident that bioptic driv-ing would also be a feasible
option in Europe. Defin-ing a solid protocol for bioptic driving
based on local
B. J. M. Melis-Dankers et al. 8
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legislation, and reproducing some of the promising re-sults
achieved in the United States in a Dutch setting,are considered to
be the first steps towards legalizationfor bioptic driving in the
Netherlands. From this pointof view, Royal Visio, National
Foundation for the Vi-sually Impaired and Blind, planned the
demonstrationproject AutO & Mobiliteit.
As no practical expertise on the subject of biop-tic driving was
available in the Netherlands, wethoroughly reviewed the existing
scientific literature(Melis-Dankers, Kooijman, Brouwer, Wieselmann,
andWitvliet, this issue). There were no serious objections
tostarting an explorative demonstration project on biopticdriving
in the Netherlands. Visio joined forces with sci-entific and public
institutes, specialist driving schools,and the official Netherlands
Bureau of Driving SkillsCertificates (CBR). The process of
introducing biop-tic driving in the Netherlands and acquiring the
neces-sary knowledge and experience is described in detail
byKooijman and coworkers (this issue). Based on our re-view of the
scientific literature and expert information,we generated an
interdisciplinary assessment and train-ing protocol for bioptic
driving. This paper describesour protocol and the data of the
demonstration projectAutO & Mobiliteit. It is important to note
that none ofthe subjects could obtain the legal right to drive by
par-ticipating in our project, simply because bioptic drivingis not
allowed in the Netherlands.
Since this is the first publication of a practical biop-tic
driving project outside the United States, it might beof interest
to organizations in other countries who maybe considering the
adaptation of driving licence regu-lations to increase the mobility
options for the grow-ing population with moderate visual
impairments. Inthe meantime, several European research groups
haveshown an interest in the topic, and a German consor-tium has
already started to study bioptic driving (PRI-AMOS, Project
Initiative zur Auto-Mobilität von Men-schen mit
Seheinschränkungen, Düren, Germany; per-sonal communication,
April 2007).
METHODSOur protocol is largely based on the current prac-
tice in Berkeley California (Professor Ian L. Bailey,
op-tometrist, and Helen Dornbusch, mobility instructor,School of
Optometry, University of California, Berke-ley, California, USA)
and the Schepens Eye ResearchInstitute (Professor Eli Peli,
optometrist, Harvard Med-
ical School, Boston, Massachusetts, USA, and RenéPaquin, MEd,
certified orientation and mobility spe-cialist, Crotched Mountain
School, Greenfield, NewHampshire, USA), and has been adapted to the
situ-ation in the Netherlands.
SettingThe sector Assessment and Rehabilitation of Royal
Visio, National Foundation for the Visually Impairedand Blind in
the Netherlands, consists of 12 regionalinstitutes which provide
visual rehabilitation services tothe northern, western, and eastern
parts of the Nether-lands. About 500 professionals support people
whohave low vision or who are blind in their goal to livean
independent life despite their visual impairment.The services,
which are delivered on an extramural ba-sis, include
ophthalmologic, sensory and perceptual vi-sual assessments, low
vision services, social work, anda wide variety of rehabilitation
training. The institutesare mainly financed by the national
healthcare insur-ance system, as a result of which most
rehabilitationservices are free of charge for low vision
clients.
Collaboration and Allocation of TasksThe project was organized
simultaneously at 2 re-
gional institutes of Visio (in Haren and Apeldoorn).Visio was
responsible for the general project coor-dination, the recruitment
of subjects, visual as wellas neuropsychological assessment,
subject counseling,predriving training with a bioptic, and the
collectionand evaluation of data. The Department of Ophthal-mology
of the University Medical Center Groningen(UMCG) supervised the
scientific embedding of theproject and the selection of the
subjects (ACK). TheDepartment of Psychology of the University of
Gronin-gen and the Department of Neurology of the UMCGwere
concerned with the monitoring of progress in driv-ing performance
in the course of the project (WHBand RBB). Two driving schools,
specializing in drivingwith physically impaired people, performed
the driv-ing screening for subject inclusion and gave the
drivinglessons (Niemeijer, Scheemda for the northern part ofthe
Netherlands; Welzorg, ‘s-Hertogenbosch for the restof the country).
The CBR (Rijswijk), the official driv-ing licence authority in the
Netherlands, was respon-sible for the final on-road testing of
practical fitnessto drive. In order to minimize unforeseen
problems, afeedback committee consisting of 6 experts (in
driving
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regulation, ophthalmology, low vision rehabilitation,low vision
patient network, low vision research, anddriving research) operated
in the background to adviseon issues vital for the success of the
project.
Training of ProfessionalsAs no practical experience of driving
with bioptics
existed in the Netherlands, all professionals involvedhad to be
informed about and trained in all aspectsof the procedure. This
process is described in detail byKooijman and colleagues (this
issue).
BiopticDetailed information on the variety of bioptic de-
vices available and their specific use for driving is pro-vided
by Melis-Dankers et al (unpublished data, 2008)and Peli.22 In this
demonstration project we used anOcutech VES-mini telescope (3 × 8;
Ocutech, ChapelHill, North Carolina, United States,
www.ocutech.com;see Figure 1). The main characteristics of this
Kepleriansystem are its small size, its large field of view
(14.7◦),its high optical quality, and its low weight (17 g).
Thetelescope yields a sharp overall image without colorshifting or
aberrations. The small exit pupil has to bealigned carefully with
the eye pupil. Furthermore, ac-cording to the manufacturer’s
specifications, the tele-scope provides for refractive error
correction (internal
TABLE 1 Inclusion and exclusion criteria
Inclusion criteria• Binocular BCVA without bioptic: (Lighthouse
ETDRS 2000 chart at 4 m and 500 lux) 0.16–0.50 (20/125–20/40)•
Monocular BCVA with telescope 0.5 (20/40) or better• Ophthalmologic
situation stable for at least 1 year• Binocular horizontal field of
view ≥140◦ (Goldmann III-4e)• Peak log contrast sensitivity within
normal limits (Vistech VCTS6500 ≥ 1.6 at 3–6 cycles/degree [B5 or
C4])
Exclusion criteria• Only 1 functional eye• Peripheral visual
field defect (Goldmann)• Absolute central scotoma (Goldmann +
Amsler test)• Diplopia (without telescope)• Significant
metamorphopsia (Amsler test at 30 cm and 1000 lux)• Cerebral
vascular accident• Posttraumatic amnesia >1 week• Coma >1
day• Possible signs of dementia, attention, or memory disorders
- Trail Making Test A + B (A, B, and/or B/A below 10th
percentile)- Mini Mental State Examination (MMSE; only used for
subjects > 65 years, MMSE < 25)
• Psychiatric treatment within the past 5 years• Hearing
impairment• Problems with balance or orientation
by focus +12/–12 diopters) and has a closest near focusof about
23 cm at emmetropic setting. These featuresallow subjects to use
the aid in a wide variety of every-day situations, which was
expected to have a positiveeffect on the use of the bioptic while
driving. The useof only one type of telescope for all subjects
allowedeasy disassembly and reuse of the telescopes.
The telescope was fitted monocularly, allowing thedriver to
improve visual acuity with 1 eye whilst preserv-ing the overall
field of view with the other eye. Duringthe assessment phase,
clip-on telescopes were availablewhich could be attached to any
pair of glasses to givean impression of the use of a bioptic and to
test thegeneral visual performance of the candidates. Distantvisual
acuity through the clip-on telescope had to be0.5 (20/40) or better
to continue participation in theproject. After passing the
assessment phase, a perma-nent bioptic was fitted individually by
the low visionspecialist.23,24 The monocular telescope was
mountedin the upper part of the carrier lens of either the bestor
the dominant eye, depending on the subject’s pref-erence.
Subject RecruitmentA complete overview of the inclusion and
exclusion
criteria is shown in Table 1. These criteria were largelybased
on national legal regulations5,25 and our literature
B. J. M. Melis-Dankers et al. 10
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review (Melis-Dankers et al., this issue). Candidateswere
continually recruited between May 1, 2004, andApril 30, 2006,
through publicity about the project innational and regional
newspapers and among regularclients of Visio. Over this 2-year
period, 378 peopleapplied voluntarily for participation or
additional in-formation. All applicants were contacted, mostly
bytelephone, which revealed that 135 of them did notfulfill the
inclusion criteria or were not interested infurther participation
because of the expenses and ef-forts attached to participation and
the uncertainty ofwhether bioptic driving would be legally
permitted inthe Netherlands in the near future. The remaining
243candidates received additional information about theproject.
Special attention was paid to their motives forparticipating, the
general risks related to driving withlow vision, possible
alternative forms of transportation,and the financial costs of
participation for the subjects.Assessments, additional travelling
expenses, and thepredriving training were paid for by Visio and the
on-road test of practical fitness to drive was free of chargefor
the subjects as well, but the costs of the individualdriving
lessons and the bioptic device had to be paidfor by the subjects
themselves. On the basis of the in-formation provided, 218
candidates agreed to receive aprinted questionnaire with questions
related to the in-clusion criteria and detailed written information
aboutthe project. In total, 160 questionnaires were returned(73%).
The total number of subjects to be included inthe demonstration
project was not determined before-hand. We estimated that at least
8 to 10 bioptic drivershad to pass the official on-road test of
practical fitnessto drive in order to start the procedures that
might leadto legalization of bioptic driving in the
Netherlands.Based on the expert information provided and our
lit-erature review, we tried to select the candidates whowere most
likely to pass the fitness to drive test with-out requiring a large
number of driving lessons. Of thecandidates who returned the
questionnaire, 75 candi-dates were preselected on the basis of the
informationthey had provided about their general medical
history,their ophthalmic disorder and its stability, their
moti-vation for participating, visual acuity, and visual field.If
needed, detailed recent ophthalmologic informationabout candidates
was requested from their own ophthal-mologists. At the beginning of
the project, we includedequal numbers of new and experienced
drivers. Becauseit soon appeared that new drivers needed a
substantialnumber of lessons to attain the minimum level of
driv-
ing skills required for the assessment of practical fitnessto
drive, we subsequently tended to prefer older and ex-perienced
drivers. Based on the information about thecandidates, we selected
36 subjects during the 2-year pe-riod: 26 males and 10 females,
between the ages of 18and 81 (median = 38, first quartile = 28,
third quartile= 56). These 36 subjects were invited to one of the
2participating institutes of Visio for an assessment day(25 in
Apeldoorn and 11 in Haren).
The first selection of candidates was made prior tothe
assessment day on the basis of visual acuity, visualfield, and the
ophthalmic disorder and its stability, asprovided by the candidate
or their ophthalmologist.The selected 36 subjects were tested for
all inclusionand exclusion criteria during the assessment day.
Thevisual performance with a bioptic was measured with aclip-on
model on the assessment day.
Inclusion AssessmentThe assessment day started with a low vision
assess-
ment by a low vision specialist (Table 1). Subjects whofulfilled
all optometric inclusion criteria proceeded toan informational
interview with 1 of the client coun-selors. During this interview,
the questions of the sub-ject were answered, and the project
details, driving his-tory, and motivation for participation were
discussedon the basis of a questionnaire.
Next, an orientation and mobility (O&M) trainer ob-served
the subject’s viewing behavior in a number ofdaily mobility
situations, with and without a clip-ontelescope. The subjects had
to demonstrate attentiveviewing behavior in everyday traffic
situations compa-rable to normal pedestrians. During this mobility
test,the trainers also checked for balance or orientation
dis-orders.
To exclude subjects with dementia and learning, at-tention, or
memory disorders, a neuropsychological testbattery consisting of
the Trail Making Test versions Aand B,26,27 and the Mini Mental
State Examination(MMSE)28 were administered by a psychologist.
Initially, the assessment day did not include a behind-the-wheel
screening test for driving. From the 16th sub-ject onwards, we
introduced a preliminary screening testfor driving on the
assessment day to avoid high ex-penses of driving lessons in cases
where general drivingskill was low. In this test, one of the
driving instructorsjudged the driving experience and viewing
behavior ofthe subject in regular traffic without a bioptic. The
last
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21 subjects were only included in the project if the driv-ing
instructor was satisfied with their aptitude to drive.The
assessment day ended with a concluding conversa-tion with the
client counselor during which remainingquestions of the subject
were answered. Subjects had tosign an informed consent form. All
assessment resultswere evaluated by both clinical physicists (A. C.
K. andB. J. M.), who decided whether to admit the subjects tothe
subsequent training program. Only after admission,a customized
bioptic telescope system was fitted by thelow vision
specialist.
Predriving TrainingBy far the most important factor to be
learned with
regard to the bioptic is that the telescope is used onlyvery
briefly and at specific moments. Almost all driv-ing is done while
looking through the carrier lens. Thetelescope is used only as an
aid to inspect details and tospot distant objects briefly, allowing
better anticipationof traffic situations ahead. Prolonged searching
throughthe telescope must be avoided. The bioptic telescopespotting
action can be compared with the way a reg-ular driver glances into
the rearview mirror. Secondly,the bioptic driver has to become
accustomed to inte-grating the enlarged monocular image of the
telescopeinto the complete visual field. Alertness to changes inthe
periphery while glancing through the telescope isassumed to be an
advantage. As the view through thetelescope must not last longer
than about a second, thecombined eye and head movement has to be
goal di-rected and perfectly timed. In addition, one has to getused
to objects and movements appearing to be largerand closer when seen
through a telescope. Practice inusing the system in a smooth and
coordinated manneris necessary to obtain continuous visual
perception andto prevent the subject from becoming disoriented.
To develop the proficient use of the bioptic, 4 indi-vidual
weekly training sessions of 3 hours each weregiven by one of the
O&M instructors. The subjectslearned to use the customized
bioptic correctly in every-day situations (except behind-the-wheel
driving). Sub-jects had to practice using the bioptic on the days
be-tween the weekly training sessions (homework), and tokeep a
diary about frequency, location, and duration ofpractice and
weather conditions. If possible, they alsopracticed locating and
recognizing signs as a passengerin a car driven by a family member
or acquaintance.Each training session started by checking that the
sub-
ject had mastered the goals of the previous training ses-sions
and ended with an evaluation of the session andan explanation of
the homework.
Training Session 1
The goals of the first training session were that thesubjects
were able to spot and recognize pictures, andread some words
through the telescope. They first hadto spot stationary objects
whilst standing indoors. Thesubjects were instructed to make the
appropriate headand eye movements and to decrease the duration
ofspotting. The exercises included the recognition of dif-ferent
pictures and symbols on a wall, as well as readingwords (direction
signs), and instant selection of rele-vant information. If
successful, instruction continuedwith moving objects. They also had
to perform viewingtasks outdoors standing beside a road.
Training Session 2
The goal of this session was to increase viewing speed.The
subjects had to read cards held up for a short dura-tion by the
instructor. In addition, the subjects learnedto spot stationary and
moving objects while walking.They were instructed to spot through
the telescope atthe right moment for only a second or less. Several
slideswith pictures of traffic signs were used. Most of the
traf-fic signs were recognized by looking through the
carrierlenses, but sometimes the use of the telescope was
nec-essary to identify certain details. A comparable exercisewas
carried out in normal traffic situations while walk-ing outside.
The subjects also practiced the use of theirbioptic while being
driven around as a passenger in acar on highways and quiet roads.
They had to detectsigns along the road through the carrier lenses
and todecide whether it was necessary to look through thetelescope
to see more details. They were instructed touse the telescope at
the right moment. If they spottedtoo early they were not able to
read the sign, and if theyspotted too late there was not enough
time to respondproperly. The subjects also visited a large
departmentstore or do-it-yourself shop where they had to
performvarious viewing tasks in a cluttered visual environment.Here
they could experience how the bioptic could alsobe used for other
tasks and at various distances.
Training Session 3
During this session, the exercises were aimed at thecorrect
judgement of traffic situations and developing
B. J. M. Melis-Dankers et al. 12
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the habit of anticipating and looking ahead. The sub-jects had
to scan quickly projected slides of traffic situa-tions through the
carrier glasses and use their telescopeto inspect the sites with
important information in moredetail. As a passenger they learned to
look ahead tojudge each situation in time and to select the
importantvisual information. Road signs had to be recognizedand
read. Subsequently, the subjects had to navigateindependently by
finding a route to an arbitrary cho-sen destination, reading road
signs and giving directionsto the driver. Meanwhile, they had to
report verbally onthe presence of other road users and on important
in-formation such as speed limits and stop signs.
Training Session 4
In addition to a repetition of previous exercises, theuse of the
bioptic was practiced in combination withthe car’s mirrors. As
passengers, the subjects “drove”various routes in complex and heavy
traffic situationswhile carrying out traffic-related viewing tasks
with theirbioptics.
At the end of the fourth session, the overall viewingbehavior
with the bioptic was evaluated and it was de-cided whether the
subject could progress to the drivingtraining. The subjects had to
master all the describedviewing exercises with their bioptic
without exception.If the O&M instructor deemed it necessary, a
fifthpredriving training session was organized.
Driving TrainingThe driving lessons were given in a regular
learner
car with automatic transmission by one of the 2
drivinginstructors, both specialized in driving with
physicallyimpaired people, in either the city of Groningen or
’s-Hertogenbosch. Each week, two 1-hour driving lessonswere given
with a short intermediate break. The sub-jects were instructed to
adjust the telescope to infinityeach time they took their place
behind the wheel. Thedriving instructors trained the drivers to
navigate inde-pendently through traffic, to drive safely and
smoothly,and to perceive essential information in time to
reactadequately.
To monitor driving performance in the course of thelessons, the
structured protocol of the Test Ride forInvestigating Practical
fitness to drive (TRIP)29−32 wasused. This test assesses whether
the driver demonstratessufficient general driving skills and
compensates ade-quately for the visual impairment. The standard
TRIP
protocol was extended to include a number of itemsto assess the
use of the bioptic. The protocol used con-tained 64 different items
in 11 categories, each scored ona 3-point scale (“sufficient,”
“doubtful,” “insufficient”),evaluating specific driving skills and
behavior (e.g., po-sition on the road, following distance, speed,
and com-munication with other road users).
At the beginning of our demonstration project, thedriving
instructors followed their normal routine andonly paid special
attention to the correct viewing behav-ior with the telescope when
necessary. As they graduallylearned that instructions on correct
viewing behaviorhad a positive effect on both viewing and driving
per-formance, they paid more attention to the proper useof the
telescope while driving. To limit the subjects’and the project’s
expenses, the maximum number ofdriving lessons was originally set
at 24. A subject wasonly allowed more lessons on the strong
positive adviceof the driving instructor. When the driving
instructorwas satisfied regarding the driving of the subject
ac-cording to general standards, the driving of the subjectwas
scored according to the TRIP protocol31 When theglobal TRIP scores
were “sufficient,” the subject was rec-ommended to the CBR for the
on-road test of practicalfitness to drive.
Practical Fitness to DrivePractical fitness to drive was
examined independently
by an official CBR expert on fitness to drive in thesame city
where the driving lessons had been given.These CBR experts are
specialized in the examination offunctionally impaired drivers and
have been educatedregarding medical disorders as related to driving
and carmodifications. In practice, they use a practice
guidancesystem that guarantees the uniformity and quality ofthe
assessment. The on-road test of practical fitness todrive is
defined in the Dutch Regulations for MedicalFitness to Drive.25 It
is considered the golden standardin the Netherlands for determining
the practical fitnessto drive in people with impairments. It is not
a regu-lar driving examination, but a special test drive to
de-termine whether a driver compensates adequately forfunctional
limitations, leading to safe and smooth driv-ing. For our project
this implies that, ideally, the visualimpairment and the use of the
bioptic are not noticeableoutside the car. During this one-hour
test drive, variousaspects were assessed regarding the safety and
smooth-ness of driving while using the bioptic. More detailed
13 Driving with Bioptics in the Netherlands
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situation-related performance was systematically scoredwith the
TRIP-protocol.29−32 The most important re-sult of the assessment is
the global rating of practicalfitness to drive. For our
demonstration project, we dis-tinguished between “unfit and denied
retest,” “unfit butallowed retest after additional lessons,” and
“fit whenusing the bioptic.” The final judgement on the prac-tical
fitness to drive was left solely to the CBR expert.Since bioptic
driving for people with visual acuity worsethan 0.5 (20/40) is not
yet allowed in the Netherlands,successful subjects did not obtain a
driving licence.
RESULTSInclusion Assessment
Sixteen of the 36 subjects (Table 2, subjects 1–16,44%) were
excluded because they did not meet the re-quirements on 1 or more
tests. Two others (subjects 17and 18) met all the test criteria,
but withdrew of theirown volition before the start of the
predriving trainingbecause they were not willing to travel the
required dis-tance for the driving lessons and training sessions,
andalso considered the expenses to be too high.
Despite our precautionary measures, 7 subjects (19%)did not meet
our visual acuity criteria, either with orwithout a telescope. One
subject appeared to have avisual acuity without a telescope that
was worse than theinclusion threshold of 0.16 (20/125), and 6
others didnot reach the required acuity of 0.5 (20/40) with the
clip-on telescope for the preferred eye. All of the latter hada
visual acuity in the range 0.16–0.20 (20/125–20/100)without a
telescope. Two of these 7 subjects could havepassed the visual
acuity criteria by wearing the telescopeon the better, nondominant
eye, but they opted not todo this.
Five subjects (14%) had a significant loss of peak con-trast
sensitivity, and 2 subjects (6%) did not meet ourvisual field
criteria. Seven subjects (19%) scored too lowon the basis of the
neuropsychological test results, 3 sub-jects (8%) showed improper
viewing behavior with thebioptic during the O&M screening, and
2 (6%) had anunstable ophthalmologic condition. Although the
se-lection of all subjects was based on the information pro-vided
by their ophthalmologist, 10 of them (28%) wereexcluded due to
insufficient visual acuity with or with-out the bioptic, reduced
visual field, or unstable oph-thalmic condition. The actual driving
performance wasscreened in 12 of the 18 excluded subjects on the
assess-ment day, and 5 of them scored negatively on that test.
Two of the excluded subjects decided on the assess-ment day to
withdraw regardless of the test results, be-cause they anticipated
that the training would be too fa-tiguing and/or the investment in
both time and moneywas considered to be too high (subjects 10 and
16).
Six of the excluded subject held a driving li-cence. Five of
them had extensive driving experience(>50.000 km) in the past.
The licences of 7 others hadexpired. Five subjects never owned a
driving licence,but 3 of them had taken driving lessons before.
The remaining 18 subjects proceeded to the predriv-ing training:
14 males and 4 female between the ages of18 and 72 years (median =
34, first quartile = 26, thirdquartile = 48 years), 12 in Apeldoorn
and 6 in Haren(Table 3, subjects 19–36). They suffered from a
varietyof eye diseases: juvenile/congenital macular degenera-tion
(4), age-related macular degeneration (2), albinism(4), optic
atrophy (3), retinal vascular occlusion (1), andretinal
degeneration (4). The visual acuity of the eyepreferred for the
telescope, as measured through thecarrier glass, ranged from
0.25–0.45 (20/80–20/44; me-dian = 0.30, first quartile = 0.25,
third quartile = 0.30).Looking through the customized telescope,
the range ofthe visual acuity increased to 0.55–1.10
(20/36–20/18;median = 0.79, first quartile = 0.71, third quartile
=0.79).
The mean actual gain in visual acuity due to the useof the
telescope was 2.7 ± 0.4 ×, range 2.2 × –3.2 ×).Although,
theoretically, a gain of better than 3× is notpossible for a 3×
magnifying telescope, these findingsfall well within the
test-retest variability for the ETDRSchart.34 The visual acuity in
the other eye ranged from0.08–0.40 (20/250–20/50; median = 0.25,
first quartile= 0.20, third quartile = 0.30).
Of our subjects, 12 preferred to view through thetelescope with
the dominant eye. For 2 of them thiswas the eye with the lower
acuity. Six subjects chose toview through the telescope with the
nondominant eye,with equal (2) or better acuity (4) compared with
thedominant eye. Five subjects with increased glare sensi-tivity
preferred the telescope to be mounted in carrierglasses with a
light absorbing filter (subjects 21, 24, 30,33, and 34).
None of these 18 subjects suffered from additionalvisual field
defects, and their neuropsychological testsmet the inclusion
criteria. All had normal peak con-trast sensitivity in the eye with
the telescope, however,3 subjects showed reduced peak contrast
sensitivity inthe fellow eye.
B. J. M. Melis-Dankers et al. 14
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TAB
LE2
Ch
arac
teri
stic
so
fex
clu
ded
sub
ject
s
Nr
Ag
e(y
ear)
Gen
der
Dri
vin
glic
ence
Dri
vin
gex
per
ien
ce
Eye
dis
ease
cate
go
ry
Pref
erre
dey
efo
rte
lecs
cop
e
VA
wit
ho
ut
tele
sco
pe
VA
wit
hcl
ip-o
nte
lesc
op
eG
ain
Log
(pea
kco
ntr
ast
sen
siti
vity
)
Vis
ual
fiel
dh
ori
zon
tal
(deg
)
Dri
vin
gsc
reen
ing
test
Pass
edas
sess
men
td
ay
Rea
son
for
excl
usi
on
134
fy
3A
OD
0.15
0.40
2.7
1.6
180
–n
va+
(vt)
221
fn
0G
OD
0.16
0.49
3.1
1.9
180
–n
vt+
(op
)3
73f
e3
BO
D0.
160.
503.
11.
518
0y
ncs
+(o
m)
420
mn
1A
OS
0.19
0.45
2.4
1.6
140
nn
vt+
(ds)
527
me
3F
OS
0.19
0.35
1.8
1.6
–y
nvt
619
mn
0F
OD
0.20
0.45
2.3
1.6
–n
nvt
+(n
p/o
m/d
s)7
81m
e3
BO
D0.
200.
402.
01.
718
0n
nvt
+(d
s)8
45m
e3
FO
S0.
200.
351.
81.
414
0y
nvt
+(c
s/o
m/n
p)
940
fy
3D
OD
0.22
0.60
2.7
1.6
180
–n
op
1054
fy
2A
OD
0.25
0.85
3.4
1.5
160
yn
oi+
(cs)
1181
me
3B
OS
0.25
0.69
2.8
1.6
140
–n
np
1268
me
3B
OD
0.30
0.89
3.0
1.6
160
nn
ds
+(n
p)
1351
my
3B
OD
0.32
0.72
2.3
1.6
130
–n
vf+
(np
)14
28f
n1
GO
D0.
391.
263.
21.
418
0–
ncs
+(n
p)
1558
my
3B
OS
0.40
1.00
2.5
1.6
180
nn
ds
+(n
p)
1669
my
3G
OS
0.48
0.79
1.6
1.0
130
yn
oi+
(cs
+vf
)17
36m
n1
FO
S0.
350.
892.
51.
915
5y
yo
i18
39m
e1
AO
D0.
390.
892.
31.
915
0y
yo
i
y=
yes/
posi
tive,
n=
no/n
egat
ive;
–=
not
appl
icab
le;O
D=
right
eye,
OS
=le
ftey
e.A
ge=
age
atda
teof
asse
ssm
ent
day.
gend
er:m
=m
ale,
f=
fem
ale.
Driv
ing
licen
ce:e
=dr
ivin
glic
ence
expi
red.
Driv
ing
expe
rienc
e:0
=no
driv
ing
expe
rienc
e,1
=on
lyle
sson
s(<
1.00
0km
),2
=<
50.0
00,
3=
≥50
.000
km.
Eye
dise
ase:
A=
juve
nile
/con
geni
talm
acul
arde
gene
ratio
n,B
=ag
e-re
late
dm
acul
arde
gene
ratio
n,C
=al
bini
sm,
D=
optic
atro
phy,
E=
retin
alva
scul
aroc
clus
ion,
F=
retin
alde
gene
ratio
n,G
=an
omal
yan
terio
rse
gmen
t.VA
=vi
sual
acui
tyof
pref
erre
dey
efo
rth
ete
lesc
ope.
Gai
n=
gain
invi
sual
acui
tydu
eto
tele
scop
e.Ex
clus
ion:
cs=
cont
rast
sens
itivi
ty,d
s=
driv
ing
scre
enin
gon
asse
ssm
ent
day,
np=
neur
ops
ycho
logi
cal,
oi=
own
initi
ativ
e,om
=or
ient
atio
n&
mob
ility
scre
enin
g,op
=op
htha
lmic
inst
able
,va
=vi
sual
acui
tyw
ithou
tte
lesc
ope,
vf=
visu
alfie
ld;v
t=
visu
alac
uity
thro
ugh
clip
-on
tele
scop
e.Bo
ldfo
ntin
dica
tes
that
the
asse
ssm
ent
resu
ltdo
esno
tm
eet
the
incl
usio
ncr
iterio
n.
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TAB
LE3
Clin
ical
char
acte
rist
ics
of
incl
ud
edsu
bje
cts
Nr.
Ag
e(y
ear)
Gen
der
Eye
dis
ease
cate
go
ryB
est
eye
Do
min
ant
eye
Pref
erre
dey
efo
rte
lesc
op
e
VA
wit
ho
ut
tele
sco
pe
Pref
erre
dey
e
VA
wit
hcu
sto
miz
edte
lesc
op
ePr
efer
red
eye
Gai
n
Log
(pea
kco
ntr
ast
sen
siti
vity
)Ey
ew
ith
tele
sco
pe
VA
oth
erey
e
Log
(pea
kco
ntr
ast
sen
siti
vity
)O
ther
eye
1918
mC
OS
OS
OS
0.25
0.71
2.8
1.6
0.20
1.6
2033
mC
OD
OD
OD
0.25
0.79
3.2
1.6
0.20
1.6
2121
mC
=O
SO
D0.
250.
552.
21.
80.
251.
822
23f
CO
DO
SO
D0.
330.
712.
21.
80.
201.
623
57m
FO
SO
DO
D0.
300.
652.
21.
60.
401.
424
32m
D=
OD
OD
0.28
0.89
3.2
1.9
0.28
1.9
2535
mF
OS
OD
OS
0.30
0.79
2.6
1.9
0.25
1.6
2621
mD
OD
OS
OD
0.25
0.71
2.8
1.9
0.16
1.8
2772
fB
OD
OD
OD
0.25
0.79
3.2
1.6
0.08
1.2
2842
mD
=O
DO
D0.
300.
852.
81.
80.
301.
629
56m
AO
SO
DO
D0.
350.
792.
31.
60.
401.
730
34m
BO
DO
DO
D0.
280.
712.
51.
60.
251.
431
34m
F=
OD
OD
0.30
0.65
2.2
1.9
0.30
1.6
3239
fA
OS
OD
OS
0.30
0.79
2.6
1.6
0.25
1.6
3365
mE
OD
OD
OD
0.45
1.10
2.4
1.6
0.33
1.6
3450
mA
=O
DO
S0.
250.
793.
21.
90.
251.
935
32f
AO
DO
DO
D0.
300.
893.
01.
60.
251.
636
24m
F=
OD
OD
0.33
0.76
2.3
1.9
0.35
2.2
OD
=rig
htey
e,O
S=
left
eye.
Age
=ag
eat
date
ofas
sess
men
tday
.Gen
der:
m=
mal
e,f=
fem
ale.
Eye
dise
ase:
A=
juve
nile
/con
geni
talm
acul
arde
gene
ratio
n,B
=ag
e-re
late
dm
acul
arde
gene
ratio
n,C
=al
bini
sm,D
=op
ticat
roph
y,E
=re
tinal
vasc
ular
occl
usio
n,F
=re
tinal
dege
nera
tion,
G=
anom
aly
ante
rior
segm
ent.
Best
eye
=ey
ew
ithbe
stvi
sual
acui
tyw
ithou
tte
lesc
ope:
“=”
both
eyes
have
equa
lacu
ity.V
A=
visu
alac
uity
(mon
ocul
ar).
Gai
n=
gain
invi
sual
acui
tydu
eto
tele
scop
e.
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TABLE 4 Driving-related characteristics of included
subjected
Nr.Drivinglicence
Drivingexperience
VA withouttelescope
VA withcustomizedtelescope
O&Mtraining(hours)
Drivinglessons(hours)
Judgementdriving
instructor
Number ofCBRtests
Practicalfitness
to driveFinal
conclusion
19 n 0 0.25 0.71 12 24 y 2 n dp: unfit/bioptic use20 n 0 0.25
0.79 12 22 y 2 n dp: unfit/nervous21 n 0 0.25 0.55 12 2 n 0 — dl:
unfit/driving aptitude22 n 0 0.33 0.71 12 2 n 0 — dl: unfit/driving
aptitude23 n 0 0.30 0.65 12 2 — 0 — oi24 n 0 0.28 0.89 14 36 y 2 n
dp: unfit/bioptic use25 n 0 0.30 0.79 12 10 — 0 — oi26 n 1 0.25
0.71 12 10 y 1 n dp: unfit/bioptic use27 e 3 0.25 0.79 12 32 y 2 n
dp: unfit/nervous28 n 1 0.30 0.85 12 36 y 2 y dp: fit with
bioptic29 y 3 0.35 0.79 12 6 y 1 y dp: fit with bioptic30 y 3 0.28
0.71 12 6 y 1 y dp: fit with bioptic31 e 3 0.30 0.65 12 28 y 3 y
dp: fit with bioptic32 e 3 0.30 0.79 15 20 y 1 y dp: fit with
bioptic33 y 3 0.45 1.10 15 14 y 1 y dp: fit with bioptic34 e 3 0.25
0.79 15 12 y 1 y dp: fit with bioptic35 e 3 0.30 0.89 12 20 y 1 y
dp: fit with bioptic36 y 3 0.33 0.76 12 6 y 1 y dp: fit with
bioptic
y = yes/positive, n = no/negative; – = not applicable. OD =
right eye, OS = left eye. Driving licence: e = driving licence
expired. Driving experience: 0 =no driving experience, 1 = only
lessons (< 1.000 km), 2 = < 50.000, 3 = ≥ 50.000 km. VA =
visual acuity. Final conclusion: dl = driving
lesson/judgementdriving instructor, dp = practical fitness to drive
test/judgement CBR-official; oi = own initiative.
Predriving TrainingThe results with respect to the driving
performance of
the 18 subjects who passed the assessment day are sum-marized in
Table 4. None of them experienced notice-able mobility, balance or
orientation problems whilstusing the bioptic, not even during the
first attempt. Ingeneral, subjects were eager to learn how to use
the biop-tic in daily mobility situations. They all mastered
thecorrect spotting technique for stationary and movingtargets
while standing still within 1 training session (3hours). Fourteen
of them finished the predriving train-ing sessions within 4 weeks
(12 hours). The other 4subjects needed an additional session to
optimize theirviewing behavior with the bioptic during movement.The
number of predriving training hours therefore var-ied between 12
and 15. Although the fourth trainingsession contained a lot of
revision exercises, the finalevaluation of the predriving training
indicated that
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the remaining 9 subjects had never owned one. Two ofthis last
group had taken driving lessons before and 3had driving experience
in vehicles not requiring a driv-ing licence (tractor, electric car
[maximum 16 km/h]and minicar [maximum 45 km/h]).
Despite the successful predriving training and thebioptic
training as a passenger, subjects experienced anoticeable
regression in their ability to use the bioptic assoon as they were
behind the wheel. The combinationof demanding traffic and the
simultaneous use of thebioptic was experienced as a difficult
task.
Because they showed insufficient aptitude for drivingaccording
to their driving instructor, 2 subjects with al-binism (subjects 21
and 22) were rejected at an earlystage of their driving lessons.
Neither of them hadprior driving experience. Their driving skill
had not yetbeen screened during the assessment day, otherwise
theywould probably have been excluded at that stage of theproject.
In fact, this experience gave the initial impetusto introduce the
driving screening test on the assess-ment day. Two others (subjects
23 and 25) withdrew oftheir own accord, 1 because a change of
employmentmade the driving lessons too tiring, and the other
be-cause the anticipated expenses of the driving lessonswere
considered to be too high.
The remaining 14 participants showed progress in thecourse of
the driving lessons resulting in safe driving andviewing behavior,
as judged by the driving instructor.In this group, the number of
driving lessons per sub-ject varied between 6 and 36 (mean 19.4 ±
10.8). Notsurprisingly, inexperienced drivers needed more
lessonsthan the subjects who obtained a driving licence once,but
they all succeeded in integrating the correct biop-tic viewing
behavior while driving, as judged by thedriving instructor. Their
global TRIP scores were “suffi-cient” and they were allowed to
proceed to the officialon-road test of practical fitness to
drive.
In our project, the subjects only drove during day-light.
Driving lessons took place during all seasons andvaried weather
conditions. Neither the subjects, thedriving instructors, nor the
CBR experts reported anyparticular inconvenience regarding the use
of the biop-tic during bad weather conditions.
Practical Fitness to DriveOf the 14 subjects who were allowed to
take the prac-
tical fitness to drive test, 7 drivers passed successfully
thefirst time (global TRIP score “sufficient” and test result
“fit when using the bioptic”). One subject was tested“unfit and
denied retest” (subject 26). He had only verylimited driving
experience and had never held a drivinglicence. This subject was
not allowed a reexamination, ashe did not demonstrate accurate
viewing behavior withthe bioptic during the examination, and the
CBR expertestimated that numerous lessons would be necessary forhim
to pass the practical fitness to drive test successfully.
The remaining 6 subjects were tested “unfit but al-lowed retest”
and were allowed a second or third test ofpractical fitness to
drive. Two of them passed that retestafter additional lessons
(subjects 28 and 31). In the be-ginning, they both had difficulty
with using the biopticadequately while driving. After specific
attention waspaid to the proper use of the bioptic for driving
bythe driving instructor, both viewing and driving perfor-mance
gradually improved to a successful level. One ofthem (subject 28)
was an inexperienced driver withouta previous licence. He needed
very specific driving andviewing instructions, but managed to pass
the final testafter 36 driving lessons. The other 4 subjects who
wereallowed a reexamination, were ultimately judged “unfitafter
retest.” Two of them had albinism and showed in-sufficient steering
performance, in particular, too muchlateral swaying (subjects 19
and 20). For one of them(subject 20), bioptic viewing behavior was
sufficientduring the lessons according to the driving
instructor,but nervousness played an important role in his
failure.The other (subject 19) did not use the telescope
oftenenough to anticipate oncoming traffic situations. Thethird
subject who tested “unfit after retest” (subject 24)was also an
inexperienced driver. Initially, he had prob-lems integrating the
use of the bioptic in the driving pro-cess. Once he started using
the device at the repeatedrequests of the driving instructor, his
driving perfor-mance began to improve. However, after 36 lessons
hisprogress was not yet sufficient to pass the practical fit-ness
to drive test. Both the driving instructor and theCBR expert felt
that this subject stood a good chance ofpassing after an additional
set of driving lessons, but theproject management considered that
this was beyondthe scope of our demonstration project. The last
subjectwho failed the retest was an experienced driver with
rea-sonably good driving performance from the start of thedriving
lessons (subject 27). Although her bioptic view-ing behavior was
correct, she did not show sufficientprogress in integrating it into
her driving performance.Also, in her case, nervousness during the
examinationsmight have played a role.
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The most striking difference between successful andunsuccessful
subjects was their previous driving ex-perience. All but 1 of the 9
successful subjects whopassed the practical fitness to drive test
were experienceddrivers. The total number of training hours
(predriving+ driving) for these successful subjects varied
between18 and 48 (mean 29.4 ± 10.6). By comparison, 6 of the7
subjects who received a negative result from the driv-ing
instructors or the CBR experts were inexperienceddrivers without a
previous licence. For 3 of them, view-ing behavior with the bioptic
was mentioned as thedecisive reason for rejection.
As can be seen in Tables 3 and 4, there is no indica-tion of a
relationship between the visual acuity, eitherwith or without a
telescope, and the outcome of thepractical fitness to drive test.
The same holds true forage, gender, eye disease, actual telescopic
gain, hours ofpredriving training, and the number of driving
lessons.
DISCUSSIONSubject Recruitment and InclusionIt appeared that we
had to include 36 subjects in or-
der to end up with 9 subjects who passed the official testof
practical fitness to drive. We do not exclude the pos-sibility that
the others can become proficient biopticdrivers, but this lies
beyond the scope of our demon-stration project, which only allowed
a limited numberof driving lessons.
Our project illustrates that each candidate under con-sideration
for bioptic driving must be looked at individ-ually, because a
complex mix of psychological, optical,motor and behavioral issues,
and driving experience isinvolved. One cannot rely solely on the
informationprovided by the candidates themselves or their
oph-thalmologists, in combination with theoretical calcu-lation of
the visual acuity through the telescope. Anindividual approach is
necessary to assess the actual vi-sual functions with and without a
bioptic, to examinethe viewing performance in various conditions,
and toassess practical fitness to drive.
Furthermore, a uniform information policy with re-gard to the
public is imperative to prevent false expec-tations. To avoid
mutual disappointment, we stress theimportance of the motivation of
possible bioptic driversand a clear explanation of the perspectives
to individu-als eligible for bioptic driving, including an
explana-tion of the risks of driving with low vision
withoutprofessional guidance and information about alterna-
tive means of transport. Despite our extensive efforts toinform
possible candidates about all the implications,17% withdrew from
the training program, which mighthave been prevented by an even
better information pro-cess.
Because it was made abundantly clear to all appli-cants that
participation could never lead directly to thepermission to drive,
motivation for participation wasmainly based on the prospect that a
positive outcomeof the project might promote a change in the legal
po-sition. Considering this marginal personal benefit andthe high
individual effort and expenses involved, therelatively large number
of 160 returned questionnairescan be seen as a sign of the
importance of independentdriving in our current society, even for
visually impairedpeople.
BiopticSeveral models of spectacle-mounted bioptic tele-
scopes are currently available.22,34–36 Our Ocutech VESmini
telescope has a fixed magnification of 3×. Sub-jects with a visual
acuity worse than 0.16 (20/125) the-oretically need more than 3×
magnification to reachthe limiting acuity value for driving of 0.5
(20/40). Thehigher the magnification, the more difficult it
becomesto achieve a stable image during fixation37 Neverthe-less,
in the United States, drivers sometimes use largermagnifications of
up to 6×.38 On the other hand, sub-jects with a relatively high
visual acuity of close to 0.5might actually prefer a telescope with
a lower magnifi-cation. For this reason, our choice for a 3×
telescopein this study must be considered a compromise. In fu-ture
applications, we will consider a customized mag-nification,
obviously on the condition of an optimaltelescopic field of
view.
As the bioptic is a rather expensive aid that users haveto pay
for themselves, we preferred to provide a versatilemodel. After
discovering the benefits of the telescopeduring the predriving
training, subjects appreciated thevariable focus and used the
bioptic in various daily sit-uations for far as well as near
vision.
Predriving TrainingBoth subjects and driving instructors
reported that
they considered training as essential to becoming ac-quainted
with the correct use of a bioptic and to in-tegrate the viewing
behavior when driving.16,39−45 Ourpredriving training was aimed at
training the subjects to
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process all information continually, to decide which ob-jects
have to be inspected in more detail, to catch theseobjects within
the field of the telescope instantly, andto read or distinguish the
essential information quicklyand without losing their overview.
Although subjects ex-perienced these tasks as very strenuous and
fatiguing inthe beginning, they all gradually mastered the
techniqueand became accustomed to it in normal everyday mo-bility
situations within 12–15 hours of training. This iscomparable with
the predriving training time suggestedby Park and associates.46 for
inexperienced telescopeusers, but substantially less than the 55
hours of train-ing time advised by Huss.47,48 From discussions with
thesubjects, the driving instructors, and the CBR officials,the
predriving training appears to function well, and wehave no reason
to expect that changing the predrivingtraining would significantly
improve the outcome interms of practical fitness to drive.
Driving LessonsAlthough all subjects mastered the correct
bioptic
viewing behavior before they started the driving lessons,the
integration with driving was experienced as a diffi-cult task. This
was even true for the experienced drivers.It appears that bioptic
viewing and driving are 2 com-plex tasks that do not integrate
automatically whentaught separately. There was no apparent
difference inthis process between younger and older drivers.
Albinism and Nystagmus
Of the subjects included, 4 had congenital albinismaccompanied
by nystagmus (subjects 19–22). Duringthe first months of the
project, the driving instructorsand the CBR experts noticed that
these subjects showeda marked swaying steering behavior while
driving. Somedriving experts recalled this behavior from earlier
per-sonal experience with applicants with nystagmus. Sincethe other
project members were not aware of a relation-ship between lateral
sway while driving and albinismor nystagmus, we did a literature
search in the PubMeddatabase (repeated on January 30, 2007) with
the key-words “driving AND nystagmus” and “albinism ANDdriving.”
None of the 70 hits found showed any re-lationship between
nystagmus and lateral sway duringdriving except in combination with
alcohol abuse oruse of medication. On the contrary, in the
literatureon bioptic driving, subjects with albinism are
generallyidentified as ideal candidates.41,49−54 In general,
theyhave normal visual fields and contrast sensitivity, and
as they have moderate-to-low vision from birth, most ofthem are
used to the loss of visual acuity. The fact thatall 4 subjects with
albinism were beginner drivers mightexplain why they showed a
larger amount of lateral swaythan the experienced ones. The project
management de-cided to exclude subjects with albinism and
nystagmusfrom our demonstration project as this finding obvi-ously
lies beyond the scope of the current project. Fur-ther scientific
research is needed to establish the role ofnystagmus with respect
to bioptic driving.
Practical Fitness to DriveAll successful subjects except one
were experienced
drivers and had previously owned a driving licence.Previous
driving experience, while vision was still good,appears to be
beneficial when learning to drive with abioptic. From this it might
be concluded that peoplewith congenital forms of low vision are
somewhat ata disadvantage compared with those with acquiredloss of
visual acuity. The driving experts indicated thata driving
experience of 36 hours or less is relativelylittle for new drivers
to demonstrate practical fitnessto drive. To conform to the experts
general experience,new drivers might need more lessons, but, taking
intoaccount the high costs and the uncertainty of a legalpermit to
drive, this was rejected by the project man-agement. If bioptic
driving becomes legally permittedin the Netherlands, further
research is needed to designeffective training methods for
inexperienced driverswith reduced visual acuity.
We did not find a relationship between the visualacuity, either
with or without the telescope, and theoutcome of the practical
fitness to drive test. However,only subjects with a visual acuity
of 0.25 (20/80) orbetter appeared to progress to the driving phase
of ourdemonstration project. As we used a very strict and
se-lective inclusion protocol, it cannot be concluded fromthis
study that subjects with a visual acuity worse than0.25 are unable
to drive with a bioptic telescope system.
Correct viewing behavior with the bioptic in generalmobility
situations is no guarantee of successful use ofthe bioptic during
driving. Subjects reported that the in-tegration of the acquired
bioptic viewing behavior intothe driving situation was a strenuous
task that neededattention and training. During the course of the
project,we learned that more attention had to be paid to theuse of
the bioptic and the integration of bioptic use fordriving.
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The project has been a learning exercise not only forthe
subjects, but also for the professionals. Each of theprofessionals
involved is an expert on a particular partof the protocol, but none
of them had practical expe-rience with the use of a bioptic in
driving. To succeedrequired comprehensive training, an
interdisciplinaryapproach, an agreed protocol, conscientious
documen-tation of the results, mutual exchange of knowledge,and an
open discussion of specific findings.
A step-by-step evaluation of our protocol led us tothe
conclusion that none of the consecutive parts canbe omitted as yet,
and that each of the profession-als plays an indispensable role. We
have no apparentreason to change our original inclusion criteria at
thistime. In future, the assessment of viewing behavior withthe
bioptic after the predriving training may need tobe objectified. If
regulations are changed and biopticdriving becomes legal in the
Netherlands, we urgentlyadvise using a comparable protocol for
testing candi-dates eligible for bioptic driving. In such a
situation,subjects could be allowed more driving lessons if
nec-essary, and one might consider using various types oftelescope
to meet individual needs even better. Beforebioptic driving in
dusky and dark situations is allowed,information is necessary about
the use of the bioptic atnight and whether this requires additional
training andtesting.
CONCLUSIONThis is the first study in Europe to prescribe
biop-
tic telescopes for driving and to train bioptic drivers.During
the study, 18 subjects were successfully trainedin the use of a
bioptic telescope system in daily mo-bility situations. Of these, 9
passed the official on-roadtest of practical fitness to drive of
the CBR, which isthe official driving licensing authority in the
Nether-lands. This indicates that, after careful selection
andtraining, safe and smooth bioptic driving is possible onan
individual basis in Dutch traffic, and probably in theEU. We
advocate legislation in the EU to allow peoplewith moderately
reduced visual acuity to demonstratetheir practical fitness to
drive by performing an indi-vidual on-road test conducted by the
national officialdriving licensing authority. Currently, action is
beingtaken with the responsible national authorities to regu-late
bioptic driving in the Netherlands. Balancing gen-eral traffic
safety and individual freedom of mobilityof people with reduced
visual acuity is an important
and complex issue. We advise an individually
tailoredinterdisciplinary approach, in which the actual
drivingperformance is considered.
ACKNOWLEDGMENTThe authors wish to thank the driving schools
Welzorg (‘s-Hertogenbosch) and Niemeijer (Scheemda)for their
participation. Jos de Vries, Sander Bison, ArieZwijgers, and Rene
Stofkooper of the Netherlands Bu-reau of Driving Skills
Certificates (Rijswijk) are grate-fully acknowledged for assessing
the practical fitnessto drive, and Mark Tant (Belgian Road Safety
Insti-tute, Brussels, Belgium) for sharing his expertise on
thelegal aspect of driving in Europe. We give thanks toPetra
Pijnakker, Eelco van Pluuren, Birgit van Iddekinge,and Irene
Wanders (all Visio) for the assessment andtraining of all
participants. Jose van Rosmalen (Viziris,Utrecht) and Fokke Jan
Postema (Isala Hospital, Zwolle)are greatly appreciated for their
contribution to the feed-back committee. Ilja Wieselmann is
acknowledged forassisting with searching out literature and
proofreading.Finally, we thank the anonymous reviewers and Eli
Pelifor their very useful remarks and suggestions.
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